Adducts of alkarylborates with trialkylphosphites or alkyl sulfoxide



3,082,169 ADDUCTS F ALKARYLBORATES WITH TRIAL- KYLPHOSPHITES' 0R ALKYL SULFOXIDE Edward L. Kay, Akron, Ohio, and Edwin C. Knowles,

Ponghlreepsie, N.Y., assignors to Texaco Inc, New

York, N.Y., a corporation of Delaware No Drawing. Filed Sept. 23, 1960, Ser. No. 57,913

9 Claims. (Cl. 252-463) This invention relates to a novel composition of matter and to an improved lubricant containing saidmoyel composition as an additive and exhibit-ing. ;de sii3ablythigh extreme pressure properties. More particglgrly, this invention relates-to hydrocarbon and synthetio base lubricating oils containing an adduct of a borate ester and an alkyl phosphite or an alkyl sulfoxide.

There is an ever increasing need for the improvement of the extreme pressure properties of lubricating oils with ful in the formulation of jet engine lubricants.

in accordance with the present invention novel compositions of matter are prepared by reacting a borate ester with alkyl phosphitesor alkyl sulfoxides thereby forming adducts ofsaid materials. An improved lubricating composition having increased load-carrying properties is obtained by the inclusion of from 0.1 to 5.0 weight percent, preferably 1 to 3 weight percent, of the novel adduct compounds of the presentinvention in lubricating oils. The

preferred additives are adduets of tri-(nonylphenyl) borate and tri-Z-ethylhexyl phosphiteor dimethyl sulfoxide.

The method of preparing the adduct additive of the present invention is by slowly adding, with agitation the donor molecule, that is, the phosphite or sultoxide to the borate. The reactions for the preparation are as follows:

. wherein R may be the same or different hydrocarbyl radicals preferablyalkyl, aryl, alkaryl and aralkyl radicals and R is a monovalent hydrocarbyl radical containing from 1 to 24 carbon atoms and preferably from 1 to carbon l atoms.

Examples of the various borate esters used to form the adducts of thepresent invention are: trihexyl borate,

trioctyl borate, trinonyl borate, tridecyl borate, tridodecyl flborate, tricyclohexyl borate, trihexylphenyl bot-ate, trioctylphenyl borate, trinonylphenylborate, dip-chlorophenyl-monononylphenyb borate, tri-(m,p)-cresyl borate and tridodecylphenyl borat'e. r

Examples of the various alkyl phosphites that are reactedwith the borate esters to form the adducts of the present invention are tri-Z-ethylhexylphosphite, tri-methyl phosphite, tri-ethyl phosphite,trbZ-methylhexyl phosphite,

-tri-cyclohexy-l phosphi-te, tri-isopropyl phosphite, tri-2-iso- .propylhexyl phosphite,. tri-2-ethylcyclohexyl phosphite, tri-2-methylcyclohexyl phosphite, tri-Z-isopropyl-cyclohexyl phosphite, tri-nonyl-phosphite and trinonylphenyl phosphite.

Examples of the various alkyl sulfoxides that are reacted with the borate esters to form the adducts of the present invention-are: dimethyl sultoxide, diethyl sulfbxide, diisopropyl sulfoxide, di-butylsulfoxide, diamyl 70 sulfoxide, dihexyl sulfoxide, dicyclohexyl sulfoxide, di-

j U i d tates Patent 0 Patented Mar. 19, "1963 nonyl sulfoxide, dinonylphenyl sulfoxide and didodecyl stability and viscosity-temperature properties as well as.

sul-foxide.

The lubricating oils of this invention include mineral oils and synthetic lubricating oils. The mineral oils found to be useful for this invention include oils having a vis oosity in the range required for lubricating fluids and in particular hydrocarbon mineral oils which include, paraflin base, naphthene base, mixed paraflin-naphthene base and mineral oils of the residual or distillate type. The hydrocanbon lubricating base generally has been subjected to solvent refining to improve its oxidation and thermal solvent dewaxing to remove waxy components and to improve the pour properties of the oil. Broadly speaking, hydrocarbon lubricating oils having an SUS viscosity at F. of between 50 to 700 are used in the formulation of the improved lubricants of this invention.

The mineral lubricating oils to which the additive adducts of this invention are added usually contain other additives designed to impart desirable properties thereto. For example, viscosity index improves such as the polymethacrylates having a molecular weight ranging from 500 to 25,000 are usually included therein. The V1 'improver normally used is a polymethacrylate having the following recurring structural unit:

wherein R is an aliphatic radical ranging from 4 to 18 carbon atoms and n is an integer of more than 1.

The esters which constitute the synthetic lubricant composition of this invention are broadly described as esters of hydrocarbyl carboxylic acids. They are high molecular weight materials of lubricating oil characteristics derived from alcohols which are usually aliphatic alcohols containing 1 or more hydroxyl radicals and monocarboxylic acids which are usually aliphatic carboxylic acids containing 1 or more carboxylic acid radicals.

Widely used synthetic ester lubricants areali-phatic diesters of aliphatic dicarboxylic acids containing 6-42 carbon atoms. From the standpoint of cost and availability, the preferred dibasic acids are adipic acid, sebacic acid and azelaic acid. The aliphatic alcohols used to form the diesters usually contain at least 4 carbon atoms and up to 20 or more carbon atoms. C to C alcohols are most commonly used. Ether alcohols such as Cellosolve and Car-bitol may also be used in the formation of the aliphatic diesters of organic dicarboxylic acids used as .the lubricating base in the compositions of this invention. Alcohols containing 2 or more hydroxyl radiwls and no hydrogen substituted on the beta carbon atom such as trimethylol propane and pentaerythritol have proven particularly effective in formulating stable high temperature ester lubricants.

Examples of alkyl esters of aliphatic carboxylic acids are the following: di-isooctyl azelate, di-Z-ethylhexyl seb. acate, di-Z-ethylhexyl azelate, di-Z-ethylhexyl adipate, dilauryl azelate, di-sec-amyl sebacate, di-Z-ethylhexyl alkenyl-succinate, di-2-ethoxyethyl sebacate, di-2-(2'-methoxy.- ethoxy) ethyl sebacate, di-2-(2'-ethylbutoxy) ethyl sebacate, di-Z-butoxyethyl azelate, di-2-(2'-butoxyethoxy) ethyl alkenyl-succinate, pentaerythritol tetracaproate and trimethylol propane tri-isooctanoate. I

In addition to such esters, polyester lubricants formed by a reaction of an aliphatic dicarboxylic acid, a dihydroxy compound and a monofunctional compound, which is either an aliphatic monohydroxy alcohol or an aliphatic monocar-boxylic acid, in specified mol ratios are also employed as the synthetic lubricating base in the compositions of this invention; polyesters of this type are described in US. 2,628,974 on Polyester Synthetic Lubricants, which issued to R. T. Sanderson on February 17, 1953. l'olyesters formed by reaction of a mixture containing specified amounts of 2-ethyl-1,B-hexanedtol, sebacic acid, and Z-cthylhexanol and by reaction of a mixture containing adipic acid, diethylene glycol and 2- ethylhexanoic acid illustrate this class of synthetic polyester lubricating bases.

The sulfur analogs of the above-described esters are also used in the formulation of the lubricating composttions of this invention. Dithioesters are exemplified by di-Z-ethylhexyl thiosebacate, di-n-octyl thioadipate and the dilaurate of 1,5-pentanedithiol; sulfur analogs of polyesters are exemplified by the reaction product of adiphic acid, tltioglycol and Z-ethylhexyl mercaptan.

Alkyl-substituted phenols are usually incorporated tn the lubricants of the invention as anti-oxidants. The preferred and most commonly used alkyl phenol antioxidants is 2,6-di-tertiary octylphenol; 2,6-di-tertiary amyl 4 methylphcnol; and 2,6-di-isopropyl-4-methylphenol. Hindered phenols of this type are employed in concentrations between 0.1 and 1.0 weight percent.

Although hindered phenol type anti-oxidants are the most widely used anti-oxidants in the lubricant compositions of the invention, aryl-substituted amine anti-oxidants such as pltenylnaphthylamine, phenylene diamine, and diphenylamine are also used in lubricants in conjunction with the extreme pressure additive of the invention. The amine anti-oxidants are employed in the same concentrations as the hindered phenol anti-oxidant.

Organic silicones are normally incorporated in the lubricants of the invention to impart thereto anti-foam properties. The silicones are usually of the dialkyl or mixed alkyl-aryl silicone type. Dimethyl silicone is normally employed as the anti-foam agent. The silicone is incorporated in the lubricant by means of a kerosene concentrate containing 5 to weight percent silicone. A very satisfactory anti-foam agent is a kerosene concentrate 10 weight percent dimethyl silicone. The kerosene concentrate is employed in an amount sufficient to provide a silicone polymer concentration of from 50 to 250 parts per million based on the total lubricant composition.

To demonstrate the excellent improvement in the loadcarrying ability of lubricating oils containing the additive complex of the present invention, the compositions were subjected to the I.A.E. Gear Test. The I.A.E. Gear Test is one of the requirements of British Specification D.E.R.D. 2487, Lubricating Oil, Aircraft Turbine Engine." The I.A.E. Gear Test is also designed to evaluate the scutl-limited load-carrying ability of aircraft gear lubricants.

The results of the I.A.E. Gear Test on lubricating oil compositions of the present invention are set forth in the following table:

I TABLE I I.A.E. Gear Test Oil: Tooth Load, lbs. Base oil A 18 Base oil A plus 1.25 wt. percent tri-(nonylphenyl) borate 68 Base oil A plus 1.25 wt. percent tri-Z-ethylhexyl phosphite Base Oil A plus 2.0 wt. percent tri-(nonylphenyl) borate adduct of:

Tri-2-ethylhexyl phosphite 75 Dimethyl sulfoxide 60 N. B.--No test data obtained on dimethyl sulfoxlde alone in base 011 because of its insolubility.

solvent dewaxed and has an SUS viscosity of 100 at 100 F.

Base oil A gave an I.A.E. Gear Test value of 18. Table 1 demonstrates the improvement in toudarrying ability of the base oil when the additives o the present invention are included therein, the LAB. Gear Test gave a value of from 60 to 75 for all the samples tested that contained the adduct additives of tri alkaryl borate and alkyl phosphite or sulfoxide of the present invention, whereas the base oil containing the non-adducted phosphite gave a reading of 25 and the non-adducted sulfoxide was insoluble in the hydrocarbon oil. Even though the base oil plus the borate alone gave a favorable reading of 68, it will be seen from the following table that the.

hydrolytic instability of the borate precludes its use as a lubricant oil additive.

To demonstrate the hydrolytic stability of the adducts of the present invention 5 milliliters of water were added to 25 milliliters of the compounds as shown in Table 11 below. The samples were allowed to stand for one hour at ambient temperature. The amount of precipitate present, (boric acid) in the sample was then estimated.

TABLE II Hydrolylic Stability Compound: Amount precipitate Tri-(nonylphenyl) borate Heavy Tri-(nonylphenyl) borate tri-2-ethylhexyl phosphite adduct Trace Tri-(nonylphenyl) borate dimethyl sulfoxide adduct Slight The above demonstrates the hydrolytic instability of the tri-(nonylphenyl) borate as compared to the relatively stable adducts of the present invention.

To demonstrate the oxidation stability of the adducts of the present invention the lubricating oils containing these adducts were subjected to the G.M.. Oxidation Test," the results of which are shown below in Table III.

The GM. oxidation procedure is as follows:

The Saybolt Universal viscosity at 210 F. is determined on the original sample.

Two hundred grams (14).! gram) of the original sample are weighed into a tared 400 ml. beaker; the beaker with its contents are placed on the turntable in the oven, which is maintained at 325 F. (12 F.). The temperature of the oven is read from an ASTM loss on heat thermometer placed in one of the samples on the shelf. The thermometer is observed through the glass window, without opening the door. Rotation of the shelf is maintained at all times, even during temperature observation. The turntable is rotated at a speed of 5 to 6 rpm. After hours, the beaker is removed from the oven, allowed to cool and reweighed. After the measurement of the evaporation loss, stir the lubricant thoroughly in order to distribute any precipitate uniformly throughout the oil. Weigh out approximately 10 grams of the lubricant into an Erlenmeyer fiask of 125 ml. capacity, noting the weight to 0.1 gram. The lubricant remaining after removing the samples for this test is retained for the viscosity test. By means of a graduated cylinder, add 90 ml. of precipitation naphtha, stopper the flask, shake thoroughly and allow to stand for one hour at a temperature of 25 C. At the end of the one hour period filter the mixture through a Gooch crucible that has been previously dried and weighed. Wash the precipitate with a small amount of precipitation naphtha. Allow the suction to continue for five minutes to dry the crucible. Place the crucible in a drying oven at C. for one hour cool in a desiccator and weigh.

The lubricant remaining, after removing the samples for the Insoluble Material Test," should be allowed to viscosity at 210 F. is determined upon the decanted portion of the sample.

TABLE III G. M. Oxidation Test 100 F. Neut. Amount Oil Kin. Vis. No.

Inc., Inc, Sludge percent Base Oil 13 ll 0.4 trace. Base Oil I3 plus 1.25 wt. percent tri- 23 0.6 trace. (nonylphcnyl)bornte.

Base Oil B plus 2.0 wt. percent tri- (nonylphenyl) bornlc utlduct oi:

'Iri-2-ethylhoxyl phosphite 6 0v 2 slight. Dilnethyl sulioxiile I 28 0. 6 slight.

Base oil B is a parafiin based distillate which has been furfural refined. lightly acid treated, clay contacted and solvent dewaxed and hasan SUS viscosity of 325 to 350 at 100 F. v

The oxidation data shown in Table III above indicates the superiority of the adduct of tri-(nonylphenyl) borate with tri-Z-ethylhexyl phosphite. Although the adduct of tri(nonylphenyl) borate and dimethyl sulfoxide gave data comparable to that of the borate alone, it must be remembered from Table II that the borate alone is hydrolytically unstable and therefore not feasible as a lube oil additive.

We claim:

1. An adduct composition consisting of an alkaryl borate ester and a reactant selected from the group consisting of tri-(Z-ethylhexyl) phosphite and an alkyl sulfoxide.

2. An adduct composition consisting of tri-(nonylphenyl)borate and a reactant selected from the group consisting of tri-(Z-ethylhexyl) phosphite and dimethyl sulfoxide.

3. An aduct composition consisting of equal molar,

amounts of tri(nonylphenyl) borate and Iri-(Z-ethylhexyl) phosphite.

4. An adduct composition consisting of equal molar amounts of tri(nonylphenyl) borate and dimethyl sulfoxide.

5. A lubricating composition containing a major portion of a lubricating oil and an adduct consisting of an alkaryl boratc ester and a reactant selected from the group 8. A lubricating composition containing a major por-v tion of a lubricating oil and an adduct consisting of equal molar amounts of tri-(nonylphen yl) borate and tri-Z- (ethylhexyl) phosphite.

9. A lubricating compositioncontaining a major portion of a lubricating oil and an adduct consisting of equal molar amounts of tri(nonylphenyl) borate and'dimethyl sulfoxide.

References Cited" in the file of this patent UNITED STATES PATENTS 2,160,881 Loane et al. June 6, 1939 2,160,917 Shoemaker et al. June 6, 1939 2,648,696 Whetstone Aug. 11, 1953 2,816,128 Allen Dec. 10, 1957 2,956,869

DeGray Oct. 18, 1960 

1. AN ADDUCT COMPOSITION CONSISTING OF AN ALKARYL BORATE ESTER AND A REACTANT SELECTED FROM THE GROUP CONSISTING OF TRI-(2-ETHYLHEXYL) PHOSPHITE AND AN ALKYL SULFOXIDE. 